Semi-submersible rigs are widely used in offshore oil and gas exploration and completion operations and in particular in deep sea environments where sea-bed supported rigs are impracticable. A typical semi-submersible rig comprises a slip jointed marine riser connecting the rig floor above sea level to the well-head on the sea floor. A landing/running string is deployed within the marine riser. During exploration and completion operations there is normally a need to control downhole equipment remotely from the rig floor, to convey measurements made downhole to the rig floor or to convey power to the well-head. Communication between downhole equipment and the rig floor is normally by electrical or hydraulic links that run within the marine riser. Communication between the rig floor and well-head may involve many such electrical and hydraulic links. Thus, the electrical and hydraulic links are often bundled together and sheathed in a rugged material. Such a sheathed bundle of links is termed an umbilical within the oil and gas industry.
An umbilical contains links that are liable to sustain damage, in particular as the semi-submersible rig rises and falls with the tide and seas on its slip-jointed marine riser. Thus, it is desirable to provide some form of protection for the umbilical. It is known in the oil and gas industry to use cable protectors, such as those described in GB 2377717. Such known cable protectors have a cylindrical hinged body that clamps one or more cables to the landing/running string.
The present inventor has appreciated that known arrangements for protecting cables, such as those of GB 2377717, present problems when applied to protecting an umbilical.
It is an object of the present invention to provide apparatus for protecting an umbilical.
It is a further object to provide apparatus for protecting an umbilical when used with a landing/running string, e.g. in a sub-sea oil or gas exploration or recovery procedure.